Fix test failure on analyzer bot

runtime/observatory/tests/service/developer_extension_test.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 // VMOptions=--error_on_bad_type --error_on_bad_override
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:developer';
 import 'package:observatory/service_io.dart';
 import 'package:observatory/cpu_profile.dart';
@@ skipping 38 matching lines @@
 
 void test() {
   registerExtension('__delay', Handler);
   registerExtension('__error', Handler);
   registerExtension('__exception', Handler);
   registerExtension('__null', Handler);
   registerExtension('__nullFuture', Handler);
   registerExtension('__success', Handler);
   bool exceptionThrown = false;
   try {
-    registerException('__delay', Handler);
+    registerExtension('__delay', Handler);
   } catch (e) {
     exceptionThrown = true;
   }
   expect(exceptionThrown, isTrue);
 }
 
 var tests = [
   // Initial.
   (Isolate isolate) async {
     var result;
@@ skipping 36 matching lines @@
     expect(result['type'], equals('_extensionType'));
     expect(result['method'], equals('__success'));
     expect(result['parameters']['isolateId'], isNotNull);
     expect(result['parameters']['apple'], equals('banana'));
 
 
   },
 ];
 
 main(args) async => runIsolateTests(args, tests, testeeBefore:test);